Biomarkers may predict active uveitis

A pilot study shows that 2 biomarkers in the S100 family reflect active uveitis, and could potentially be used for making therapeutic decisions.

Without biomarkers to determine if durable remission has been achieved, it is extremely difficult to determine when to stop immunomodulatory therapy in a patient who exhibits no active anterior chamber inflammation for prolonged periods. S100 protein subtypes, which are valuable biomarkers in different types of juvenile idiopathic arthritis and other autoimmune diseases, may provide a potential answer to serologically determine when ocular inflammatory disease has become inactive and is in durable remission.

This prospective study focuses on 3 phagocyte specific subtypes: A8, A9 and A12. Serum S100A8/A9 and S100A12 concentrations were significantly elevated in both the juvenile idiopathic arthritis associated uveitis (JIAU) and idiopathic anterior uveitis (IAU) groups compared to non-uveitic controls (P<0.05). Within the JIA subgroup, S100A8/A9 and S100A12 levels were elevated in patients with clinically active uveitis compared to clinically inactive uveitis (both P=0.03).

Additionally, S100A8/A9 aqueous levels were substantially higher in both the JIAU as well as the IAU groups compared to non-uveitic controls. Interestingly, these anterior chamber S100 protein levels did not correlate with serum S100 levels or with systemic immunosuppressive therapy.

The fact that the serum levels of these S100 protein subtypes are elevated in active uveitis alone and in the absence of active arthritis, particularly when markers for systemic inflammation such as C-reactive protein values are normal, makes the S100A8/A9/A12 potentially very useful serologic biomarkers for uveitis activity and disease remission. It is likely that S100 proteins produced by phagocytes within ocular tissues are released into the circulation through a breakdown of the blood aqueous barrier that is inherently present in patients with chronic anterior uveitis. This may be the reason why serum levels of these proteins are elevated with localized ocular disease only.